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PubMed1986

Oxidation of amines by yeasts grown on 1-aminoalkanes or putrescine as the sole source of carbon, nitrogen and energy.

The maximum growth rate of Trichosporon cutaneum CBS 8111 in chemostat cultures was 0.185 h-1 on ethylamine and 0.21 h-1 on butylamine, that of Candida famata CBS 8109 was 0.32 h-1 on putrescine. The amine oxidation pattern of the ascomycetous strains studied, viz. Candida famata CBS 8109, Stephanoascus ciferrii CBS 4856 and Trichosporon adeninovorans CBS 8244 was independent of the amine that had been used as the growth substrate. It resembled that of benzylamine/putrescine oxidase found in other ascomycetous yeasts. However, differences in pH optimum and substrate specificity were observed between the amine-oxidizing systems of these three species. The amine oxidation pattern of cell-free extracts of Trichosporon cutaneum CBS 8111 varied with the amine that was used as growth substrate. The enzyme system produced by Cryptococcus laurentii CBS 7140 failed to oxidize isobutylamine and benzylamine, and showed a high pH optimum. The synthesis of amine oxidase in the four yeast strains studied was not repressed by ammonium chloride and was weakly repressed by glucose but was strongly repressed if both compounds were present in the growth medium.

Amines↗

PubMed1975

Distributional patterns of mesophilous and thermophilous microfungi in two Bahamian soils.

This study focuses on the characteristics displayed by mesophilous and thermophilous microfungal populations occurring in two tropical monodominant plant communities, a Cocos nucifera grove and a Casuarina equisetifolia forest, that provide distinctly different edaphic conditions. The mesophilous population sampled at 25 degrees C by the dilution plate method and the thermophilous population that developed on soil plates incubated at 45 degrees C consisted of 1693 isolates representing 60 species and 29 genera and 8887 isolates representing 20 species and 10 genera, respectively. The mesophilous propagules averaged 9,990 per gram dry soil in the coconut grove that lacks a litter layer, is low in moisture and organic matter and is subjected to high solar irradiation. The population was characterized by the prevalence of aspergilli and dematiaceous-sphaeropsidaceous forms and the near absence of mucoraceous isolates. Ascomycetes were common. The only widespread taxa were the three species, Aspergillus niger, Penicillium chysogenum, and Cladosporium cladosporioides. Species diversity was high and 73% of the isolates were cellulolytic. In the casuarina forest, adequate moisture and organic matter and a protecting litter layer provide a mesic environment. The mean number of mesophilous fungi per gram dry soil was 32,800. This figure is considerably lower than ones reported for mesic temperate communities and may be due to more rapid propagule removal through accelerated microfaunal and microbial activity. An abundance of mucoraceous and moniliaceous isolates and penicillia, and the rarity of aspergilli, dematiaceous-sphaeropsidaceous forms and ascomycetes characterize the population. The infrequency of aspergilli is thought to be due to their poor competitive ability. Eight species, Absidia cylindrospora, Penicillium notatum, Pestalotia cocculi?, Cylindrocarpon heteronema, Gliocladium roseum, Trichoderma viride, Paecilomyces marquandii, and Penicillium funiculosum were widespread in the area. Species diversity equaled that observed in mesic temperate communities. Less than one third of the isolates were cellulolytic. Phytopathogens were common, a feature characteristic of tropical populations. Thermophilous fungi averaged 33 per gram dry soil in the casuarina forest and increased to 943 per gram in the insolated soil of the coconut grove. Thermotolerant forms (94% of the isolates) were abundant and were principally species of Aspergillus and Chaetomium. Thermophilic fungi werur species, Ch. osmaniae, Ch. medusarum, Ch. sulphureum, and Thielavia arenaria, appear to be new records for western hemisphere soils.

Bahamas↗

PubMed1995

Phylogenesis of fission yeasts. Contradictions surrounding the origin of a century old genus.

The phylogenesis of fungi is controversial due to their simple morphology and poor fossilization. Traditional classification supported by morphological studies and physiological traits placed the fission yeasts in one group with ascomycetous yeasts. The rRNA sequence comparisons, however, revealed an enormous evolutionary gap between Saccharomyces and Schizosaccharomyces. As shown in this review, the protein sequences also show a large gap which is almost as large as that separating Schizosaccharomyces from higher animals. Since the two yeasts share features (both cytological and molecular) in common which are also characteristic of ascomycetous fungi, their separation must have taken place later than the sequence differences may suggest. Possible reasons for the paradox are discussed. The sequence data also suggest a slower evolutionary rate in the Schizosaccharomyces lineage than in the Saccharomyces branch. In the fission yeast lineage two ramifications can be supposed. First S. japonicus (Hasegawaea japonica) branched off, then S. octosporus (Octosporomyces octosporus) separated from S. pombe.

Base Sequence↗

PubMed1995

A year-round study on functional relationships of airborne fungi with meteorological factors.

Air sampling was conducted in Waterloo, Canada throughout 1992. Functional relationships between aeromycota and meteorological factors were analysed. The meteorological factors were, in descending order of importance: mean temperature, minimum temperature, maximum temperature, mean wind speed, relative humidity (RH), rain, maximum wind speed and snow. The most important airborne fungal propagules in descending order were total fungal spores, unidentified Ascomycetes, Cladosporium, Coprinus, unidentified Basidiomycetes, Alternaria and unidentified fungi. Most airborne fungal taxa and highly significant relationship with temperature, but Aspergillus/Penicillium, hyphal fragments were positively associated with wind speed. In comparison with other airborne fungal taxa, Leptosphaeria and unidentified Ascomycetes were more closely correlated with rain and RH during the growing season.

Air Microbiology↗

PubMed1996

Nucleotide sequence and expression of the gene encoding NADP+- dependent glutamate dehydrogenase (gdhA) from Agaricus bisporus.

The gene encoding NADP+-dependent glutamate dehydrogenase (gdhA) was isolated from an Agaricus bisporus recombinant phage lambda library. The deduced amino acid sequence would specify a 457-amino acid protein that is highly homologous in sequence to those derived from previously isolated and characterized genes coding for microbial NADP+-GDH. The open reading frame is interrupted by six introns. None of the introns is located at either one of the positions of the two introns conserved in the corresponding open reading frames of the ascomycete fungi Aspergillus nidulans and Neurospora crassa. Northern analysis suggests that the A. bisporus gdhA gene is transcriptionally regulated and that, unlike the case in ascomycetes, transcription of this gene is repressed upon the addition of ammonium to the culture.

Agaricus↗

PubMed2004

The yeast flora of some decaying mushrooms on trunks of living trees.

Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.

Agaricales↗

PubMed1998

Identification of the first fungal annexin: analysis of annexin gene duplications and implications for eukaryotic evolution.

Annexin homologues have been found in animals, plants, and distinct protist lineages. We report the identification of the first fungal annexin, encoded by the anx14 gene of the filamentous ascomycete Neurospora crassa. Annexins have a complex evolutionary history and exhibit a large number of gene duplications and gene losses in various taxa, including the complete loss of annexin sequences from another ascomycete, the budding yeast Saccharomyces cerevisiae. Surprisingly, the N. crassa annexin homologue is most closely related to the annexin homologue of the slime mold Dictyostelium discoideum, suggesting a phylogenetic link between cellular slime molds and true fungi. Both of these annexin homologues are closely related to the family of annexin homologues present in animals, an observation consistent with the existence of the animal-fungal clade. These data further suggest that the gene duplications that generated the family of annexin sequences present in animals, fungi, and slime molds began prior to the divergence of these taxa.

Amino Acid Sequence↗

PubMed2006

Evolution and diversification of RNA silencing proteins in fungi.

Comprehensive phylogenetic analyses of fungal Argonaute, Dicer, and RNA-dependent RNA polymerase-like proteins have been performed to gain insights into the diversification of RNA silencing pathways during the evolution of fungi. A wide range of fungi including ascomycetes, basidiomycetyes, and zygomycetes possesses multiple RNA silencing components in the genome, whereas a portion of ascomycete and basidiomycete fungi apparently lacks the whole or most of the components. The number of paralogous silencing proteins in the genome differs considerably among fungal species, suggesting that RNA silencing pathways have diversified significantly during evolution in parallel with developing the complexity of life cycle or in response to environmental conditions. Interestingly, orthologous silencing proteins from different fungal clades are often clustered more closely than paralogous proteins in a fungus, indicating that duplication events occurred before speciation events. Therefore, the origin of multiple RNA silencing pathways seems to be very ancient, likely having occurred prior to the divergence of the major fungal lineages.

Ascomycota↗

PubMed2004

Production of wood decay enzymes, loss of mass, and lignin solubilization in wood by diverse tropical freshwater fungi.

In vitro production of cellulase and xylanase was common among diverse freshwater ascomycetes and their hyphomycetous anamorphs. Production of enzymes involved in lignin degradation was rare. Most isolates were capable of causing mass loss in angiosperm wood, although values were low, at approximately 10% during a 24-week period. A few isolates caused higher mass loss of up to 26.5%, and five of these were shown to solubilize significant amounts of lignin. This is the first report of lignin solubilization by freshwater fungi. Torula herbarum (hyphomycete) and Ophioceras dolichostomum (ascomycete) produced indices of lignin solubilization equivalent to those of terrestrial white-rot basidiomycetes. In all cases wood decay was 2.2- to 3-fold higher in exposed rather than submerged conditions.

Cellulase↗

PubMed2002

Redox-mediated decolorization of synthetic dyes by fungal laccases.

Laccases from the lignin-degrading basidiomycetes Trametes versicolor, Polyporus pinisitus and the ascomycete Myceliophthora thermophila were found to decolorize synthetic dyes to different extents. Differences were attributed to the specific catalytic properties of the individual enzymes and to the structure of the dyes. Due to their higher oxidative capacities, the laccases from the two basidiomycetes decolorized dyes more efficiently than that of the ascomycete. The azo dye Direct Red 28, the indigoid Acid Blue 74 and anthraquinonic dyes were directly enzymatically decolorized within 16 h. The addition of 2 mM of the redox-mediator 1-hydroxybenzotriazole further improved and facilitated the decolorization of all nine dyes investigated. Laccases decolorized dyes both individually and in complex mixtures in the presence of bentonite or immobilized in alginate beads. Our data suggest that laccase/mediator systems are effective biocatalysts for the treatment of effluents from textile, dye or printing industries.

Anthraquinones↗

PubMed2006

Current state and perspectives of truffle genetics and sustainable biotechnology.

Mycorrhizal fungi belonging to the genus Tuber produce, after the establishment of a productive interaction with a plant host, hypogeous fruitbodies of great economic value known as ''truffles''. This review summarizes the state of art on life cycle, genetic, and biotechnological investigations of Tuber spp. The ascocarp formation in truffles is a consequence of the activation of the sexual phase of the biological cycle. The formation of a dikaryotic secondary mycelium and the karyogamy in the ascal cell (followed by meiosis with ascospores formation) have been hypothesized by several authors but some doubts yet arise from the Tuber cycle by considering that a series of abnormalities have been pointed out in respect to other Ascomycetes. It is unclear if binucleated hyphal cells are derived from the fusion of mononucleated cells belonging to mycelia from different mating types or from one only. According to the karyotypes of Tuber melanosporum, Tuber magnatum, and Tuber borchii, the numbers of hyphal chromosomes suggest a chromosome number of eight (2n); these values are in the range of those of several Ascomycetes and observed for Tuber aestivum (2n=10). The importance and growth in interest during the last years in the fungi protoplasts isolation and transformation techniques can be related to current developments in Tuber genetics and biotechnology. T. borchii could be transformed through liposome-mediated delivery of genetic material as mycelial protoplasts isolation and fusion with liposomes has already been established. On the other hand, Agrobacterium-mediated transformation has been successfully established for T. borchii.

Ascomycota↗

PubMed2002

Interaction between mating-type proteins from the homothallic fungus Sordaria macrospora.

Mating-type genes control sexual development in ascomycetes. Little is known about their function in homothallic species, which are self-fertile and do not require a mating partner for sexual reproduction. The function of mating-type genes in the homothallic fungus Sordaria macrospora was assayed using a yeast system in order to find properties typical of eukaryotic transcription factors. We were able to demonstrate that the mating-type proteins SMTA-1 and SMTa-1 have domains capable of activating transcription of yeast reporter genes. Two-hybrid analysis for heterodimerization and homodimerization revealed the ability of SMTA-1 to interact with SMTa-1 and vice versa. These two proteins are encoded by different mating types in the related heterothallic species Neurospora crassa. The interaction between SMTA-1 and SMTa-1 was defined by experiments with truncated versions of SMTA-1 and in vitro by means of protein cross-linking. Moreover, we gained evidence for homodimerization of SMTA-1. Possible functions of mating-type proteins in the homothallic ascomycete S. macrospora are discussed.

Amino Acid Sequence↗

PubMed2004

Negative selection using thymidine kinase increases the efficiency of recovery of transformants with targeted genes in the filamentous fungus Leptosphaeria maculans.

A vector system was constructed that is designed to decrease the number of transformants required to be screened when looking for gene disruption events in filamentous fungi. This vector was used to mutate two genes, an ATP-binding cassette transporter ( LmABCt4) and a two-component histidine kinase gene ( LmHK1) in the ascomycete Leptosphaeria maculans. The system uses the thymidine kinase gene from the herpes simplex virus as a negative selectable marker. Thymidine kinase expression is regulated by the TrpC regulatory elements from Aspergillus nidulans and should be applicable to other ascomycetous fungi. When thymidine kinase is expressed in the presence of particular thymidine analogues, these analogues are converted to toxic compounds which kill the cell. We also report the transformation of L. maculans using Agrobacterium tumefaciens-mediated DNA delivery.

ATP-Binding Cassette Transporters↗

PubMed2006

Characterization of the arom gene in Rhizoctonia solani, and transcription patterns under stable and induced hypovirulence conditions.

The quinate pathway is induced by quinate in the wild-type virulent Rhizoctonia solani isolate Rhs 1AP but is constitutive in the hypovirulent, M2 dsRNA-containing isolate Rhs 1A1. Constitutive expression of the quinate pathway results in downregulation of the shikimate pathway, which includes the pentafunctional arom gene in Rhs 1A1. The arom gene has 5,323 bp including five introns as opposed to a single intron found in arom in ascomycetes. A 199-bp upstream sequence has a GC box, no TATAA box, but two GTATTAGA repeats. The largest arom transcript is 5,108 nucleotides long, excluding the poly(A) tail. It contains an open reading frame of 4,857 bases, coding for a putative 1,618-residue pentafunctional AROM protein. A Kozak sequence (GCGCCATGG) is present between +127 and +135. The 5'-end of the arom mRNA includes two nucleotides (UA) that are not found in the genomic sequence, and are probably added post-transcriptionally. Size and sequence heterogeneity were observed at both 5'- and 3'-end of the mRNA. Northern blot and suppression subtractive hybridization analyses showed that presence of a low amount of quinate, inducer of the quinate pathway, resulted in increased levels of arom mRNA, consistent with the compensation effect observed in ascomycetes.

Alcohol Oxidoreductases↗

PubMed1999

Intra-specific and inter-specific conservation of mating-type genes from the discomycete plant-pathogenic fungi Pyrenopeziza brassicae and Tapesia yallundae.

In previous work, four genes involved in mating-type determination were cloned from reference strains of Pyrenopeziza brassicae; three genes, PAD1, PMT1, and PHB1 (re-named henceforth as MAT-1-1, MAT-1-4, and MAT1-3, respectively), are encoded by the MAT-1 idiomorph, and one gene, PHB2 (re-named MAT-2), by the corresponding MAT-2 idiomorph. To assess MAT gene organisation within field-populations of P. brassicae, 30 field-isolates of both mating-types from different geographical locations were analysed by PCR using primers designed for the MAT genes of P. brassicae. The results indicate that mating-type gene structure and organisation within these isolates is conserved and is consistent with the mating-type designations established by crossing experiments. The four P. brassicae MAT genes were then used as probes against gel blots of the genomic DNA of a discomycete Tapesia yallundae from the same family (Dermateaceae, order Helotiales) and one, Ascobolus stercorarius, from a distantly related family (Ascobolaceae, order Pezizales), in order to determine whether P. brassicae MAT-gene homologs were present. MAT-specific hybridisation signals were obtained with T. yallundae using all four probes. In particular, MAT-1 DNA of T. yallundae gave a strongly hybridising signal with MAT-1-4 (PMT1), a putative metallothionein gene found in the P. brassicae MAT-1 idiomorph but not in any other MAT idiomorph examined to-date. No MAT-specific hybridisation was obtained with A. stercorarius. A fragment of the MAT-2 gene of T. yallundae was obtained by PCR using degenerate primers designed to amplify the high-mobility group (HMG) domain present in other ascomycete MAT genes. Sequencing of this PCR product revealed similarities to MAT HMG domains from other ascomycetes with the greatest degree of similarity exhibited with P. brassicae. The T. yallundae HMG-DNA sequence was shown to co-segregate with mating type (MAT-2) in progeny from a sexual cross.

Amino Acid Sequence↗

PubMed2001

Molecular control of copper homeostasis in filamentous fungi: increased expression of a metallothionein gene during aging of Podospora anserina.

The lifespan of the ascomycete Podospora anserina was previously demonstrated to be significantly increased in a copper-uptake mutant, suggesting that copper is a potential stressor involved in degenerative processes. In order to determine whether changes in copper stress occur in the cells during normal aging of cultures, we cloned and characterized a gene coding for a component of the molecular machinery involved in the control of copper homeostasis. This gene, PaMt1, is a single-copy gene that encodes a metallothionein of 26 amino acids. The coding sequence of PaMt1 is interrupted by a single intron. The deduced amino acid sequence shows a high degree of sequence identity to metallothioneins of the filamentous ascomycete Neurospora crassa and the basidiomycete Agaricus bisporus, and to the N-terminal portion of mammalian metallothioneins. Levels of PaMt1 transcript increase in response to elevated amounts of copper in the growth medium and during aging of wild-type cultures. In contrast, in the long-lived mutant grisea, transcript levels first increase but then decrease again. The ability of wild-type cultures to respond to exogenous copper stress via the induction of PaMt1 transcription is not affected as they grow older.

Agaricus↗

PubMed1999

Analysis of beta-tubulin cDNAs from taxol-resistant Pestalotiopsis microspora and taxol-sensitive Pythium ultimum and comparison of the taxol-binding properties of their products.

The anti-cancer drug taxol binds to beta-tubulin in assembled microtubules and causes cell cycle arrest in animal cells; in contrast, in fungi, the effect of taxol varies. For instance, the taxol-producer Pestalotiopsis microspora Ne32, an ascomycete, is resistant to taxol (IC50 greater than 11.7 microM), whereas Pythium ultimum, an oomycete, is sensitive to taxol (IC50 0.1 microM). In order to understand the differential fungal response to taxol, we isolated cDNAs encoding beta-tubulin from both P. microspora and P. ultimum. The deduced amino acid sequence of beta-tubulin from P. microspora is very similar to those from other Ascomycetes, many of which are resistant to taxol. The sequence of beta-tubulin from P. ultimum is very similar to those from Oomycetes and non-fungal organisms, many of which are sensitive to taxol. To examine the interaction between taxol and fungal microtubules, binding studies were performed with fungal cells, using [3H]taxol. The labeled taxol was found to bind specifically to P. ultimum, but not to P. microspora. In addition, the amount of [3H]taxol specifically bound to P. ultimum was reduced by the microtubule-depolymerizing drug thiabendazole, in a dose-dependent manner. These results suggest efficient binding of taxol to microtubules in P. ultimum, but not in P. microspora, and are consistent with the differential taxol sensitivity of these two organisms. Finally a comparison of previously characterized taxol binding sites in various beta-tubulin sequences showed that beta-tubulins of taxol-sensitive organisms, including P. ultimum, contain Thr219, but beta-tubulins of resistant organisms, including P. microspora, contain Asn or Gln at this position, suggesting an important role for residue 219 in the interaction between taxol and beta-tubulin.

Amino Acid Sequence↗

PubMed2004

Pezizalean mycorrhizas and sporocarps in ponderosa pine (Pinus ponderosa) after prescribed fires in eastern Oregon, USA.

Post-fire Pezizales fruit commonly in many forest types after fire. The objectives of this study were to determine which Pezizales appeared as sporocarps after a prescribed fire in the Blue Mountains of eastern Oregon, and whether species of Pezizales formed mycorrhizas on ponderosa pine, whether or not they were detected from sporocarps. Forty-two sporocarp collections in five genera (Anthracobia, Morchella, Peziza, Scutellinia, Tricharina) of post-fire Pezizales produced ten restriction fragment length polymorphism (RFLP) types. We found no root tips colonized by species of post-fire Pezizales fruiting at our site. However, 15% (6/39) of the RFLP types obtained from mycorrhizal roots within 32 soil cores were ascomycetes. Phylogenetic analyses of the 18S nuclear ribosomal DNA gene indicated that four of the six RFLP types clustered with two genera of the Pezizales, Wilcoxina and Geopora. Subsequent analyses indicated that two of these mycobionts were probably Wilcoxina rehmii, one Geopora cooperi, and one Geopora sp. The identities of two types were not successfully determined with PCR-based methods. Results contribute knowledge about the above- and below-ground ascomycete community in a ponderosa pine forest after a low intensity fire.

Ascomycota↗